This invention relates to a system for sensing and displaying data in real time for high performance lenses used on film and video cameras for high quality motion pictures and the like and, in particular, for sensing and displaying relevant data such as the distance to the object being filmed, the focus distance of the lens, the T-Stop of the lens, the current depth of field of the lens and the focal length of a zoom lens.
In cinematography it is valuable to have certain data instantly available concerning the settings of the lens that is being used and the distance to the object being photographed, particularly when the object is moving relative to the camera, thereby requiring focus distance adjustments, and when other lens adjustments are required, such as the focal length of a zoom lens and/or the T-Stop. While such lens data is available to the cameraman (or focus puller) by looking at the lens and reading the three settings (focus distance, focal length and T-Stop) at three separate locations along the lengths of the lens, this distracts the cameraman from visually following the scene being photographed, which often includes moving objects that must be tracked. Further, when the focal length, focus distance and/or the T-Stop of the lens is changed for any reason, the depth of field of that lens also changes, as is well known in the art, but previously such data has not been instantly and automatically available and visible to the cameraman. Still further, while sensors and display devices have been used that indicate the distance from the camera to the object being photographed, heretofore that distance data has not been coordinated with the relevant lens data in real time.
Thus, it is an object of the present invention to provide an apparatus and system for sensing one or more of (a) distance to the object being filmed, (b) focus distance of the camera lens, (c) focal length of the camera lens, (d) T-Stop of the lens and (e) other similar lens data and displaying that data in real time for convenient reference by the cameraman and others. A further object of this invention is to provide a system for using such data to determine and display the depth of field instantaneously. Another object of this invention is to provide a graphic representation of the depth of field and, in particular, in direct relationship to the current focus distance and/or distance to the object being photographed. Still another object of this invention is to provide sensor arrangements for the system that are applicable to existing lenses. A still further object is to provide a sensing and display system that includes a microprocessor and memory for data specific to that lens for producing precise signals to a display unit. Other and more detailed objects of this invention will appear to those skilled in the art from the following description of the presently preferred embodiments of the invention and the accompanying drawings.